some British Fossil Crustacea. 33] 
furrow strong, slightly arched backwards, the ends reaching 
each side margin at a pomt deeply notched by the abrupt nar- 
rowing of the margin from thence to the front ; branchial fur- 
rows double, inclosing between them a narrow, pointed ridge on 
each side, which meets its opposite fellow at less than a right 
angle (each meets the midline of the back at an angle of about 
40°) on a point of the back about halfway between the nuchal 
- furrow and the posterior margin ; abdomen (including the tail- 
fins) shorter than the carapace, segments very weak, slightly 
arched, their ends triangularly pomted (ends of the second one 
not dilated), sixth longer than the preceding ones, giving origin 
to the two broad, rotundato-trigonal pair of side-flaps of the tail, 
which are very large, thin, and undivided by transverse sutures ; 
seventh segment (or middle tail-flap) subtrigonal, thicker than 
the others and tuberculated ; surface of carapace, legs and 
chele covered with large spmose tubercles and mtervening 
granules of very irregular size; first pair of feet or chele very 
large, subcompressed, fingers slender, with a row of large 
teeth on the inner edge, carpus very short, tumid, trigonal ; 
three next pair of legs slender, compressed (? apparently ter- 
minated by a blunt, trigonal, simple claw) ; fifth pair not 
seen. 
In the large, flattened, strongly toothed rostrum, rough spi- 
nose legs, the small size of the abdomen, with the general form of 
its little-arched, weak segments, and the undivided outer pair of 
tail laminze, this genus approaches the recent Galathea more than 
any other recent group, differmg im its peculiar branchial fur- 
rows and ridges, meeting at an angle on the middle of the back, 
&e. The long, dentated rostrum, large, rough, spinose tubercu- 
lation of the carapace and chele easily distmguish those large cre- 
taceous species from the diminutive genera Clytia and Glyphea 
of the oolitic rocks with which they have been hitherto con- 
founded. The type of the genus is the Astacus Leachu (Maiut.), 
to which at least the figures marked f. 1 & 4. t. 29 of the ‘ Geo- 
logy of Sussex’ refer (some of the other figures possibly belonging 
to the E. brevimana, M‘Coy). The E. Leachiiis also well figured 
and described by Reuss in his ‘ Versteinerungen der bohm. 
Kreideformation,’ and by Geinitz in his ‘Char. der Schich. u. 
Pet. des sachsisch-bohmischen Kreidegebirges.’ It is distin- 
guished by the very long, straight, narrow fingers of the chele, 
which are nearly twice the length of the basal part of the hand, 
or from their base to the carpus, and set on their mner-edge 
with a row of narrow cylindrical teeth their own length apart ; 
the whole hand (or penultimate jomt and moveable finger) 
nearly one-fourth longer than the carapace. A second species 
of large size and remarkable form occurs in the chalk of Burwell 
